Tohatsu M15d2 problems!!!

Hi all
I am working on a Tohatsu M15d2 2 stroke. Which is giving me hell!!!
I am having a very hard time starting it and when I succeed it only runs for 5 secs and then it dies again. If I apply starting fluid then it starts up and runs for a few seconds before it dies again. If I try to rev it up it goes Bwaaaa and dies.
I have tried all (well not all, because then I would have fixed it obviously). I have a spare engine, so a lot of parts to interchange.
Changed upper and lower crankcase seal to new seals. (to fix a potential crankcase leak)
Changed stator, ignition coil, CDI. No change
Changed carb to a brand new.
Changes reed and reedgaskets.
Set timing correct at idle and WOT.
Bought brand new gas (E5) 95 octane and mix 1:50.
Compression is a bit high 150 psi, but no carbon buildup, I have har the crankcase apart and could see that it was very clean inside. According to service manual it should be around 110 psi.
I have NOT changed headgasket, since it has plenty of compression.
A beer is donated to the one who can help me!
Thanks

Sounds like lack of fuel. Is the fuel pump delivering OK?

Hi Paul

Well. I have tried with 3 carb and it behaves identically. THis model has the fuelpump integrated in the carb.
THere is plenty of gasoline in the carb bowl when it dies.

I seem to be able to force it to run allthough not well, if I choke it when it is about to die. And then push in the choke again.

Any ideas?

THanks

Still sounds like fuel starvation. What is the float height?